JP2008071804A - Process for fabricating high temperature superconducting bonding element utilizing phase separation of liquid phase diffusion method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To make a joint in the process for producing a superconducting joint by forming a high temperature supercondicting thin film of three layer structure including a rare earth normal conducting phase, separating the phase by partially melting the thin film of three layer structure and forming a normal conducting layer on the supercondicting thin film. <P>SOLUTION: A three layer structure thin film of normal conducting layer/supercondicting layer/normal conducting layer is deposited. Patterning is performed by etching, or the like, to have an inclination. The superconducting thin film is melted partially and a normal conducting layer is formed. Thickness of the normal conducting layer is controlled by etching. A supercondicting thin film is deposited as an upper electrode. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

The present invention relates to a superconducting junction element using phase separation of a liquid phase diffusion method in a high-temperature superconductor and a method for manufacturing the same.

In recent years, various superconducting junctions have been produced aiming at high-sensitivity magnetometers and high-speed / low-power integrated circuits.
However, the manufacture of superconducting junctions requires a high level of processing technology, which causes a delay in popularization.
JP 2001-274471 A

In order to solve the above-mentioned object, the present invention changes a high-temperature superconducting thin film to a three-layered thin film containing a rare earth normal conducting phase in a method for producing a superconducting junction. Then, the three-layer structure thin film is partially melted to cause phase separation, and a normal conduction layer is formed on the superconducting thin film to produce a bond.

Deposit normal / superconducting / normal conducting three-layered thin films. Patterning so as to have an inclination by etching or the like. A superconducting thin film is partially melted to form a normal conducting layer. The thickness of the normal layer is controlled by etching. A superconducting thin film is deposited to form the upper electrode.

The sensor detects small magnetic flux generated from the brain, and it becomes a high-speed, low-power-consumption device for integrated circuits.

Next, the method for manufacturing the superconducting junction element according to the present embodiment will be explained with reference to FIGS.

First, as shown in FIG. 1, on a MgO substrate (1), a Gd211 (2) film having a film thickness of about 100 nm, a Y123 film (3) having a film thickness of about 200 nm, and a Gd211 (film having a film thickness of about 100 nm are formed by sputtering. 2) Deposit films continuously.

Next, a resist pattern is formed on the Gd211 (2) film by a normal lithography technique.

Next, using the resist pattern as a mask, the Gd211 (2) film, the Y123 film (3), and the Gd211 (2) film are etched at an inclination of 45 ° by, for example, phosphoric acid aqueous solution or Ar ion milling.

Next, after removing the resist pattern, the substrate is heated to the partial melting temperature, and Y211 (4) and the liquid phase are phase-separated on the surface of the Y123 film (3).

At this time, the liquid phase phase-separated from Y123 forms Gd123 (5) on the surface in contact with Gd211 (2) and Y211 (4) as shown in FIG.

Next, as a pretreatment for depositing the upper Y123 (3) film as shown in FIG. 3, for example, cleaning with ECR plasma is performed to control the Y211 film thickness (4) on the surface of the Y123 film.

By this cleaning process, the Y211 film thickness (4) can be controlled at the edge of the YBCO film.

In the superconducting junction element manufacturing method according to the present embodiment, the thickness of the barrier layer formed at the edge of the Y123 film depends on the thickness of the Y211 film. Therefore, a barrier layer having a desired thickness can be formed by previously controlling the film thickness of the Y211 film with the partial melting time (FIG. 3).

Next, a Y123 (3) film having a thickness of 200 nm is deposited and patterned by laser ablation, for example, as shown in FIG. 3 to form a superconducting layer made of Y123 (3) (FIG. 4).

In this manner, a superconducting junction element having a planar Josephson junction in which the superconducting layer Y123 (3) is joined via the barrier layer Y211 extending from the superconducting layer Y123 is formed.

As described above, according to this embodiment, the thickness of the barrier layer formed between the superconducting layer is controlled by the thickness of the Y211 film, so that the thickness of the barrier layer is uniform. A bond can be formed. Thereby, the dispersion | variation in an element can be suppressed.

In the above-described embodiment, a superconducting junction element having a planar Josephson junction in which the inclination angle of the junction is 45 ° is shown. However, a ramp edge type Josephson junction in which the inclination angle of the junction is 60 °, for example. The present invention can be similarly applied to a superconducting junction element having the following.

Furthermore, a superconducting junction element using Y211 phase-separated on the superconducting layer Y123 as a barrier layer can also be fabricated using a conventional Nb-based superconducting junction fabrication technique.

Schematic sectional view showing an example of a method for producing a high-temperature superconducting junction element of the present invention Schematic sectional view showing an example of a method for producing a high-temperature superconducting junction element of the present invention Schematic sectional view showing an example of a method for producing a high-temperature superconducting junction element of the present invention Schematic sectional view showing an example of a method for producing a high-temperature superconducting junction element of the present invention

Explanation of symbols

1 MgO substrate 2 Gd2BaCuO film 3 YBa2Cu3O film 4 Y2BaCuO film
5 GdBa2Cu3O film

Claims (2)

A method for producing a superconducting junction element, wherein a rare earth oxide high temperature superconducting thin film (RE123) is produced by phase-separating a rare earth normal conducting thin film (RE211) into RE123. A method of manufacturing a superconducting junction element, wherein an yttrium oxide high-temperature superconducting thin film (Y123) is manufactured by phase-separating yttrium normal conducting thin film (Y211) into Y123 in layers.

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